Hitherto, along with a tightened regulation on the transpiration of an ozone layer-depleting gas, a demand on the refrigerant barrier property (refrigerant permeation resistance) of a hose for transporting a refrigerant to be used for an automobile or the like has become stringent. Accordingly, for example, a resin having high crystallinity, such as a polyamide resin, has been used as a forming material for an innermost layer of the hose for transporting a refrigerant (see, for example, PTL 1 to PTL 3).
Meanwhile, along with a tightened regulation on the transpiration of an ozone layer-depleting gas, in recent years, an improvement has been made in quality of the refrigerant to be used for an automobile or the like as well. For example, an R-1234yf refrigerant (HFO-1234yf refrigerant) has been developed as an alternative refrigerant to an HFC-134a refrigerant, and is a refrigerant having low ozone depletion potential and global warming potential, thus being extremely friendly to the global environment, as compared to HFC-134a. Accordingly, the hose for transporting a refrigerant to be used for an automobile or the like is also required to have performance suited to R-1234yf.